Fuel injection system



Oct. 12, 1965 c, poss 3,211,438

FUEL INJECTION SYSTEM Filed July 17, 1961 4 INVENTOR. CLARENCE R. POSSELL Maw ATTORNEY 3,211,438 FUEL INIECTIUN SYSTEM Clarence R. Possell, Gardena, Calif. (4842 Viane Way, San Diego, Calif.) Filed July 17, 1961, Ser. No. 124,522 10 (Ilaims. (Cl. 26136) The present invention relates generally to the field of spark ignition internal combustion engines, and more particularly to a new and novel constant flow fuel injection system for use therewith.

Ahnost since the inception thereof, the spark ignition engine has depended on a suction type carburetor to combine a volatile fuel with air in such proportions as to provide an explosive mixture that is fed to the combustion chambers. Carburetors of this type have many structural and operational disadvantages, which will later be described. In an attempt to overcome these disadvantages, the structure of such carburetors available heretofore has become unduly complicated due to the use of venturi and fixed orifices, percolating devices, accelerating pumps, variable orifices, air bleeds, and the like.

While the use of a large number of orifices and venturis correct certain operational disadvantages of present day carburetors, they also give rise to an undesirable substantial loss in pressure head. In addition, when jets having relatively large openings have been embodied in a carburetor construction, it has been found that fuel enters the intake manifold in the form of large droplets, or in some instances, as a steady stream. It is well known that smooth, eflicient engine performance depends on whether the fuel mixtures entering each cylinder are uniform in strength, quality, and degree of fuel vaporization. The ideal air-fuel mixture is completely vaporized when delivered by the intake manifold to the cylinders. If such complete fuel vaporization is to be achieved, it must be at least partially carried out in the intake manifold, for as previously explained, the fuel is not normally so vaporized when delivered thereto.

Transformation of fuel from droplets or a stream to vapor after entrance thereof into the intake manifold must be completed prior to delivery of the air/ fuel mixture by the manifold to the combustion chambers in the cylinders. Obviously, this transformation must be extremely rapid. Rapid transformation of large fuel droplets from the liquid to the vapor state in the intake manifold can only be carried out under high temperature, which high temperature increases the air volume in the manifold and decreases the volumetric efiiciency of the engine.

Other operational disadvantages of suction carburetors and intake manifolds available heretofore are that an excess of ten to twelve percent fuel must be present in the intake manifold to compensate for unequal distribution to the cylinder, the throttling butterfly collects and condenses fuel coming from the carburetor, excessive fuel in the liquid form enters the cylinders and is forced downwardly into the crank case to dilute the oil therein, as well as wash the oil from the cylinder walls to increase the wear thereof and piston ring wear.

A major object of the present invention is to provide a high pressure fuel injection system which substantially eliminates the operational disadvantages of previously available suction carburetors described hereinabove by discharging the volatile liquid fuel from nozzles in the form of extremely small droplets that are each below a critical size, which size constitutes that at which the surface areas of the droplets are so related to the fuel volumes thereof that the droplets immediately vaporize at the temperature and air pressure to which they are subjected in the intake manifold.

Another object of the invention is to provide a fuel injection system that is free of venturis and jets as well as ited States Patent pressure loss in the manifold, which increases the rate of air flow to the cylinders, and so finely disperses the fuel in droplet form that not only is a homogeneous fuel/ air mixture obtained, but this mixture is attained by an actual cooling of the air as it flows through the intake manifold.

A still further object of the invention is not only to obtain a homogeneous fuel/ air mixture by reducing the fuel to droplets below the critical size, but to so effect the air/ fuel mixture that the air temperature is decreased and the density increased prior to entrance thereof in the combustion chambers that improved engine performance characteristics are achieved as a result thereof.

Yet another object of the invention is to provide a fuel injection system which so supplies a fuel/air mixture to an engine in such quantity and under such temperature and pressure that fuller charges thereof move into the cylinders at both low and high engine speed than is possible to obtain with previously available suction type carburetors, with the torque and horsepower curves of the engine being improved as a result thereof over the curves for which the engine is rated.

These and other objects and advantages of the invention will become apparent from the following description thereof, and from the accompanying drawing illustrating the same in which:

FIGURE 1 is a diagrammatic view of the fuel injection system of the present invention;

FIGURE 2 is a transverse cross-sectional view of the invention taken on line 22 of FIGURE 1; and

FIGURE 3 is a fragmentary diagrammatic View of a portion of the system shown in FIGURE 1, illustrating the manner in which the same can be modified.

With further reference to the drawings, the simplest form of the fuel injection system is shown in FIGURE 1. An elongate cylindrical tubular shell 10 is provided which has a closed rear end 12. The forward end of shell 10 develops into a first outwardly projecting flange 14.

A ring-shaped valve body 16 abuts against the forward face of flange 14. A butterfly valve member 18 is pivotally supported in body 16 by a shaft 20 that is rotatably supported in oppositely disposed bores formed in the body. An end portion 22 of the shaft projects outwardly from body'lfi and has an arm 24 rigidly affixed thereto. By means of a pivotal connection 26, the arm 24 is joined to a conventional linkage system 28 that extends to the accelerator pedal of a vehicle (not shown) powered by a spark ignition internal combustion engine on which the fuel injection system is mounted.

A further bell 30 is positioned forwardly of valve body 16, which is formed with a rearwardly disposed, outwardly projecting flange 32 that abuts against the forward face of the valve body. Aligned bores are formed in the first flange 14, body 16, and the flange 32 through which bolts 34 or other fastening means extend to hold these members together as an integral assembly. For convenience herein, the assembly is hereinafter referred to as a whole by the numeral 35.

In using the invention, the conventional intake manifold and carburetor (not shown) of a conventional spark ignition internal combustion engine 36 with which the fuel injection system is to be used are removed, and replaced by the assembly 35. Engine 36 can have any number of fuel intake ports 38, depending upon the number of cylinders therein.

A number of tubular risers 40 are provided, each of which is connected on one end to one of the intake ports 38, and on the other end to shell 10 in a manner to be in communication with the interior thereof. A swirl type nozzle 42 is provided, which when liquid fuel is discharged therethrough at a greater than a predetermined pressure it discharges as a spray in which the droplets thereof are below a critical size. A filter 44 is connected to nozzle 42 on the upstream side thereof. A tube 46 is connected to filter 44. Nozzle 42 and filter 44 are supported inside shell downstream from the butterfly valve member 18 by the tube 46, or other suitable supporting means. Tube 46 projects outwardly through shell 10 to the discharge side of a gear pump 48 that is driven by an endless belt 50 from a power take-off 52 on engine 36.

The suction of pump 48 is connected by a tube 54 to one side of a filter 56, which is in turn connected by a tube 58 to a fuel reservoir 60. A fuel by-pass tube 62 extends from a T connection 64 that is in comunication with tube 46 to one side of a metering valve 65. The other side of valve 65 is connected by a tube 66 to reservoir 60. Metering valve 65 includes a body 68 through which fuel can flow from tube 62 to tube 66. A valve member 70 is slidably movable in body 68, and when the valve member is moved, the rate at which fuel can flow through body 68 is varied as well as the resistance which the valve member will offer to the flow of fuel through the body.

A cylindrical housing 72 having a closed end 74 and an open end 76 is disposed a fixed distance from body 68. A bore 78 is formed in end 74, and valve member 70 is slidably movable in this bore. A diaphragm 80 extends transversely across the interior of housing 72 and is connected to the lower end of valve member 70. A helical spring 82 encircles valve member 70 and is disposed between the adjacent surfaces of the end 74 and diaphragm 80. A confined space 84 is defined by the interior surfaces of housing 72 and the upper surface of diaphragm 80. Space 84 is connected by a tube 86 to the interior of shell 10, downstream from valve member 18.

When the engine 36 starts to operate, and during operation thereof, the pump 48 continuously discharges fuel through tube 46 to T 64 where fuel flows through a continuation of tube 46 to T 64 where fuel flows through a continuation of tube 46 to nozzle 42. Nozzle 42 is calibrated to discharge the liquid fuel therefrom as a spray that is composed of a number of droplets 88 that are each less than critical size. The rate at which droplets 88 are discharged is dependent on the pressure at which the fuel is delivered to nozzle 42. The construction of nozzle 42 is such that the spray containing droplets 88 will not discharge therefrom until a predetermined pressure is exerted on the fuel delivered to the nozzle.

In FIGURE 1 it will be seen that the fuel not passing from the T 64 to nozzle 42 flows through by-pass tube 62 to the metering valve 65. The rate at which by-passed fuel can flow through valve body 68 and th'resistance which valve 65 offers to such fluid flow is determined by the position of valve member 70. The position of member 70 when engine 36 is idling is determined by the deformed helical spring 82 which is adjusted to hold the valve member in a substantially open position, with the major portion of the fuel by-passing to reservoir 60 and the resistance of fuel fiow through valve 65 being just suflicient to maintain the predetermined pressure on fuel flowing to nozzle 42. The butterfly member must, of course, be so positioned that the engine 36 will operate at idling speed.

The transverse cross section of shell 10 is, to a degree, critical. The horsepower of an engine is proportional to the air weight flow to the combustion chambers. The commonly accepted ratio of air to fuel for combustion in a gasoline engine is to 1. This ratio can vary to a degree either way, depending upon whether power or fuel economy is desired. If the ratio of 15 to 1 is used, fifteen pounds of air must be supplied for every pound of gasoline consumed. Inasmuch as gasoline weighs approximately 600 times as much as air, 9,000 times as much air must be furnished to an engine as gasoline if a volumetric comparison is made. Therefore, the transverse cross section of shell 10 must be such, that at the differential in air pressure which exists on the downstream side of valve member 18, and the pressure at one of the intake ports 38 when open, 9,000 times as much air will enter the bell 30 in a given time as the volume of droplets 88 discharged into shell 10.

The transverse cross section of tube 10 also determines the velocity at which the air/ fuel mixture will move therethrough to the risers 40. If a charge of air/fuel mixture for the cylinder (not shown) associated with the lowermost riser 40 in FIGURE 1 is considered to be of a volume lying between the lines A and B, this volume must move from shell 10 through the riser during the time interval the lowermost intake port 38 is open. When intake port 38 associated with the upper riser opens, a volume of the air/fuel mixture lying in shell 10 between lines B and C must flow from the shell into the engine during the time interval this port is open. During the interval the uppermost intake port 38 was open, the volume of air/ fuel mixture lying between the lines C and D in shell 10 was moving towards the lowermost riser 40. Obviously, for optimum operation of engine 36, that volume of air/fuel mixture between lines C and D must move to the position between lines A and B during the interval between the closing of upper port 38 and opening of the lower port. Therefore, it will be apparent that not only is the transverse cross section of shell 10 critical, but the longitudinal spacing of the headers along shell 10 as well. This critical longitudinal spacing of the risers can be eliminated by providing a number of jets 41, each of which discharge into the end of a riser, as will be explained in detail hereinafter.

The typical maximum torque curve of a conventional internal combustion engine equipped with a suction carburetor and an intake manifold, normally rises slowly with increase in revolutions per minute of the engine, and then prior to the mid-point of the curve starts to fall rather sharply. The typical horsepower curve for the same engine rises sharply with increased revolutions per minute, and reaches a maximum value at revolutions per minute where the maximum torque curve of the engine has fallen sharply. The reason for such a maximum torque curve on a carburetor-equipped internal combustion engine is that at high speeds the charge cannot move fast enough to fill the cylinders in the short time interval available.

The operational characteristics of an internal combustion engine as above described will be altered when the carburetor and intake manifold are removed and replaced by the fuel injection system shown in FIGURE 1. With the engine so equipped, an ample supply of a fuel/ air mixture is provided whereby each cylinder receives a full charge thereof, with each charge containing a greater quantity of air than is possible by use of a carburetor, due to cooling of the air and consequent higher density in the system as heat is removed therefrom when the liquid droplets of fuel are transformed to the gaseous state.

As a result of this action, the maximum torque curve and the maximum horsepower curve continue to rise with increased revolutions per minute until the intake valves start to float; that is, not completely open and close, due to harmonics set up in the valve springs. When the valves start to float, the horsepower curve of the engine decreases sharply. However, the maximum horsepower developed by an engine equipped with the present fuel injection system will be found to occur at substantially higher revolutions per minute than the revolutions per minute at which the maximum horsepower is obtained from the same engine equipped with a carburetor. Also, it will be found that the maximum horsepower attainable from an engine equipped with the present fuel injection system will be ten to fifteen percent higher than that attainable from the same engine when the supply therefor is provided by a carburetor.

When the engine 36 is idling, the valve member 18- is positioned as shown in FIGURE 1, and the flow of air int-o shell from hell 30 is restricted. This restricted air flow into shell 10 causes a relatively high vacuum in the shell. It will be apparent from an examination of FIG- URE 1 that a high vacuum will concurrently occur in confined space 84. Due to this vacuum in space 84, the pressure exerted by the ambient atmosphere on the surface 90 of diaphragm 80 will tend to compress spring 73 and move valve member 70 to a position where a major por tion of the fuel reaching T connection 64 is by-passed back to the reservoir 60. The portion of the fuel reaching the T connection 64 which is not by-passed back to reservoir 60, flows to the nozzle 42 at slightly above the predetermined pressure previously mentioned.

When it is desired to accelerate the engine 36, the linkage system 28 is moved to pivot the valve member 18 towards a position where it would be in coaxial alignment with the center line 92 of shell 10. Engine 36 operates at maximum speed when valve member 18 is aligned with center line 92. As valve member 18 is moved from the position shown in solid line in FIGURE 1 to a desired position apart therefrom, the rate of air flow into shell 10 increases, and the degree of vacuum therein increases. This decrease in the degree of vacuum in shell 10 causes a decrease in the differential in pressure between the ambient atmosphere and the pressure in space 8-4.

The compressed spring 82 tends to expand and move diaphragm 80 and valve member 70 towards the open end 76 of housing 72. Movement of member 70 towards open end 76 places the valve member in a position to cause decrease in the rate at which liquid fuel canby-pass through valve 65 to reservoir 60. Movement of valve member 70 towards end 76 also increases the resistance of fuel flow through body 65. This increased resistance to flow through body 65 is reflected in an increased pressure on fuel as it flows to nozzle 42. Increased pressure on the fuel at nozzle 42 results in an increased rate of discharge of the fuel therethrough.

The force provided by spring 82 as it tends to expand is so calibrated relative to the fuel pressure and fuel flow characteristics of the nozzle 42, that as an increased rate of air flow into shell 10 takes place an increase occurs in the rate of fuel flow from the nozzle. crease in the rate of air flow as well as the increase in fuel discharge from nozzle 42 provides a ratio of 9000 volumes of air to one volume of fuel droplets if an air/ fuel ratio of to l is being used.

If the transverse cross section of shell 10 and the spacing of risers 40 from nozzle 42 are sufficient to meet the same requirements at high speed operation of engine 36 as occurs at idling speed, each engine cylinder will receive a full charge of the air/ fuel mixture that is uniform and homogeneous, irrespective of the speed at which the engine operates, up to that speed where the valve springs start to float.

This concurrent in- When engine 36 is decelerated, the valve member 18 is pivoted to a position to admit less air into shell 10 and the degree of vacuum in the shell starts to increase, with consequent increase in pressure differential between the ambient atmosphere and the pressure in space 84. Diaphragm 80 and valve member 70 then move away from open end 76 to increase the rate at which fuel can flow through valve 65 and lessen the pressure on fuel as it flows to nozzle 42. This decrease in fuel pressure at nozzle 42 and the increased proportion of fuel by-passed to reservoir lessens the rate at which fuel is discharged from the nozzle. The decrease in rate of fuel flow from nozzle 42 is so related to the decreased rate of fuel flow into shell 10 that the volumetric ratio of one volume of liquid fuel to 9,000 volumes of air is maintained if a fuel/ air ratio of 1 to 15 is used. Should a lean fuel mixture of, say 1 to 13 be used, the volumetric proportion of liquid fuel discharged by nozzle 42 to air entering the shell 10 would be 1 to 7,800.

mixture.

A particularly interesting feature of the use of the present fuel injection system is that irrespective of the number of revolutions at which the engine 36 operates, the method of providing a fuel/air mixture that is uniform, homogeneous and cooler than the air which entered the bell, remains the same. In contrast to this single method of forming the fuel/ air mixture by use of the present invention, a carburetor requires preparation of the fuel/ air mixture by five different circuits as the engine operates from idling speed to full throttle. These five carburetor circuits are the float circuit, low-speed circuit, high-speed circuit, accelerating pump circuit and choke circuit. Each of these circuits provides a fuel/ air mixture having characteristics different than that provided by the other circuits, and accordingly with a carburetor it is impossible to have the uniformity of a fuel/ air mixture that is attainable by means of the present invention.

Should it be desired, the fuel injection system can be modified as shown in FIGURE 3, wherein a second nozzle 42a is provided together with a second filter 44a which are located adjacent nozzle 42 and filter 44 in shell 10. A tube 96 is connected to filter 44a, which tube extends through shell 10 to the discharge side of a pressure relief valve 98. The inlet side of valve 98 is connected by a tube 100 to a T connection 102 in tube 46.

The purpose of this modification is to permit use of a nozzle 42 that supplies droplets of fuel below a critic-a1 size for the low-speed and idling demand of the engine 36. Also nozzle 42 will supply these fuel droplets until the pressure on the fuel as it enters the nozzle will supply these fuel droplets until the pressure on the fuel as it enters the nozzle exceeds a predetermined value such as 50 lbs. psi.

The relief valve 98 is preferably spring-actuated and a normally closed type which only opens when the liquid pressure on the inlet side exceeds the predetermined value previously mentioned, which for purposes of illustration has been arbitrarily selected at 50 lbs. When valve 98 opens, fuel flows to nozzle 42a and is discharged therefrom as a spray of droplets, each of which is below the critical size. During operation of nozzle 42a, nozzle 42 continues to operate. Nozzle 42a is only used when engine 36 operates at moderate to high speed.

As the speed of operation of engine 36 is increased, the demand for the fuel/air mixture becomes greater and greater. Accordingly, the discharge rate of nozzle 42a may be four to five times that of nozzle 42. However, the discharge rates of nozzles 42 and 42a are carefully determined relative to increasing pressures on the fuel delivered thereto, and the rate at which butterfly member 18 will admit air to shell 10 is so related thereto that a constant air/fuel mixture is provided in shell 10 both when nozzle 42 is operating alone as well as in combination with nozzle 42a. When the pressure on the liquid fuel delivered to valve 98 falls below the predetermined pressure mentioned, the valve automatically closes and no further fuel is discharged therefrom. This characteristic is particularly important from the standpoint of economy, for a high rate of fuel discharge into shell 10 does not take place during the time the engine is decelerating.

Although but a single set of nozzles 42 and 42a is shown in FIGURE 3, it will be apparent that additional sets can be provided, each of which would discharge directly into one of the risers 40. Operation of the invention remains the same, irrespective of whether a single nozzle or multiple nozzles are used in forming the air/ fuel Should it be desired, a single nozzle 42 or sets of nozzles 42 and 42a can be provided for each riser 40 and mounted thereon to discharge fuel directly therein. When nozzle 42 or sets of nozzles 42 and. 42a are mounted on the risers the system operates in the same manner as that shown in FIGURE 1, except that the fuel/air mixture is formed as the air discharges from shell 10 through the risers to the intake ports 38.

The various modifications of the invention have been disclosed and described herein due to the fact that the system is adapted to be used in conjunction with any spark actuated internal combustion engine. Such combustion engines are commercially available in a large variety of designs, as evidenced by the large number of automobiles, trucks, stationary engines and marine engines currently manufactured, as well as those manufactured in the past.

When the carburetor and fuel intake manifold is removed from one of these engines, it may be necessary to modify the design of the present fuel injection system to permit the system to be operatively associated with the changed structure and in order to conform with the operating characteristics thereof. In addition to the many different makes and models of internal combustion engines encountered on the present-day market, it will be found that while the majority thereof are of the fourcycle type, a substantial number of two-cycle engines are in every day use.

In the case of an internal combustion engine having fuel intake ports on both sides thereof, the shell 10 can be extended longitudinally along the center of the engine and the risers 40 directed to the intake ports. Also, when the present system is installed on an internal combustion engine having fuel intake ports on each side thereof, two concurrently operating assemblies 35 may be disposed side-by-side in the same manner as the single assembly 35 as described in conjunction with that form of the system shown in FIGURE 1. When two assemblies 35 are so used side-by-side, the arms 24 which control the positions of valve members 18 are linked together by conventional means so that both valve members 18 occupy the same positions in shells 10 when the linkage system 28 is actuated.

Although the present invention is fully capable of achieving the objects and providing the advantages hereinbefore mentioned, it is to be understood that it is merely illustrative of the presently preferred embodiments thereof and I do not mean to be limited to the details of construction herein shown and described, other than as defined in the appended claims.

I claim:

1. A fuel injection system in combination with an internal combustion engine having a plurality of fuel intake ports, which system includes: an elongate tubular shell having a bell-shaped open end portion, with said shell being closed at the opposite end; a plurality of tubular risers which are in communication with the interior of said shell and said intake ports; a reservoir wherein a volatile liquid fuel may be stored; first means for controlling the rate of flow of air through said shell to said risers at any desired rate within predetermined limits, with each of said rates giving rise to a different pressure in said shell; second means for discharging said fuel under pressure from said reservoir at a pressure that is proportional to engine speed; third means communicating with said second means for forming said fuel under pressure into a plurality of tiny droplets below a critical droplet size that are mixed with said air to form an air/fuel mixture in said shell prior to the entrance of said mixture into said intake ports, with the rate at which said droplets are formed by said third means being mathematically related to the pressure on said fuel as it enters said third means, and said critical droplet size being that at which said droplets readily vaporize at the temperature of said air with which they mix to substantially cool the same and increase the density thereof; fourth means for varying the pressure on said fuel delivered to said third means by by-passing a portion of said fuel discharged by said second means back into said reservoir; fifth means that controls said fourth means and means connecting said fifth means with atmospheric pressure and with said shell, which fifth means as said pressure in said shell drops, actuates said fourth means to by-pass said fuel at an increasing rate to lower said pressure on said fuel at said third means to decrease the rate at which said droplets are formed, said fifth means as said pressure in said shell increases, actuating said fourth means to by-pass said fuel at a decreasing rate to increase said pressure on said fuel at said third means, with said increase and decrease of pressure on said fuel at said third means so controlling the rate at which said droplets are formed that an air/fuel mixture of uniform composition is formed with said air flowing through said shell, irrespective of which this rate may be, prior to entrance of said air into said fuel intake ports.

2. A fuel injection system as defined in claim 1 wherein said first means is a butterfly valve positioned adjacent said bell-shaped open end portion of said shell and in longitudinal alignment therewith.

3. A fuel injection system as defined in claim 1 wherein said second means is a positive displacement gear pump, means including a power take-off and an endless belt for driving said pump.

4. A fuel injection system as defined in claim 1 wherein said third means comprises a nozzle which forms said fuel into a spray composed of a plurality of tiny droplets below the critical size, with the rate at which said droplets are discharged from said nozzle being dependent upon the pressure at which said fuel isdelivered to said nozzle.

5. A fuel injection system as defined in claim 1 wherein said fourth means comprises a valve having a movable valve member, which valve member when moved varies the rate at which said fuel will be passed, with said valve member when moved also varying the resistance to the flow of fuel through said valve.

6. A fuel injection system as defined in claim 5 wherein said fifth means comprises a housing having a closed first end and at least a partially open second end, with an end portion of said valve member being slidably and sealingly mounted in a bore formed in said first end, said system further including a diaphragm connected to one end of said valve member, which diaphragm is disposed in said housing and with the interior surfaces thereof cooperatively defines a confined space, deformed spring means in said housing that at all times tend to move said valve member and diaphragm in a direction for said valve member to assume a position wherein said valve member does not offer resistance to the flow of by-passed fuel through said valve body, a tube connecting said confined space to the interior of said shell, which valve member and diaphragm are moved in a direction to further deform said spring means and position said valve member in said body to decrease the rate of by-passed fuel therethrough as the pressure in said shell decreases and the differential in pressure between the ambient atmosphere and the pressure in said confined space increases, and said diaphragm and valve member also being adapted to be moved in a direction to so position said valve member that an increase in the rate of said by-passed fuel flow can take place through said body due to the force exerted by said deformed spring, with said increase in the rate of flow of said by-passed fluid accompanied by a lessening of the pressure exerted on said fuel as it enters said third means, which increase in rate of said by-passed fluid flow is accompanied by an increase in the pressure exerted on said fuel as it enters said third means.

7. A fuel injection system as defined in claim 1 wherein said third means comprises a plurality of nozzles disposed in said shell and transversely aligned with said risers for discharging said droplets directly into said risers.

8. A fuel injection system as defined in claim 1 wherein said third means comprise a plurality of nozzles mounted adjacent said risers.

9. A fuel injection system as defined in claim 1 wherein said third means comprise first and second nozzles disposed in said shell, which nozzles are each capable of discharging said fuel as a plurality of tiny droplets, said system also including means for preventing discharge of fuel from said second nozzle until the fuel pressure at said first nozzle has exceeded a predetermined pressure.

10. In combination with an internal combustion engine having a plurality of fuel intake ports, a fuel injection system including: an elongate tubular shell open at one end and closed at the opposite end; a plurality of tubular risers communicating with the interior of said shell and said intake ports; a reservoir in which a volatile liquid fuel is stored; a positive displacement fuel pump, the inlet to which is in communication with said reservoir; means for operating said pump concurrently with operation of said engine; means for controlling the rate of air flow through said shell to said fuel; nozzle means for forming said fuel into a spray containing a plurality of tiny droplets, each of which is less than a critical size, which size is that at which the surface of said droplet is so related to the volume thereof that it will vaporize within a first time interval when exposed to air at greater than a first temperature, said droplet forming means being in communication with the interior of said shell, said forming means discharging said spray into said air after said entrance thereof into said shell but prior to the time said air enters said intake ports, said forming means being capable of discharging said droplets therefrom at a plurality of different rates, with each of said rates of discharge occurring when said fuel is supplied to said droplet forming means at a particular pressure; conduit means for continuously directing said fuel discharge from said pump to said droplet forming means and returning said fuel not discharged through said droplet forming means to said reservoir; fuel control means for regulating the rate at which said fuel is returned to said reservoir and the pressure that is maintained on said fuel at the entrance to said droplet forming means; actuating means for operating said fuel control means, and means connecting said actuator means With atmospheric pressure and with said shell, said actuating means causing said control means to by-pass said fuel to said reservoir at an increasing rate as the pressure within said shell decreases and to by-pass said fuel at a decreasing rate to said reservoir as said pressure in said shell increases, with the pressure on said fuel flowing to said droplet forming means decreasing as said pressure in said shell decreases and said pressure on said fuel flowing to said droplet forming means increasing as said pressure within said shell increases, said pressure in said shell being so correlated with the pressure in said shell that irrespective of the rate of air flow through said shell said droplets will be discharged thereinto to provide an air/fuel mixture of constant proportions.

References Cited by the Examiner UNITED STATES PATENTS 1,376,201 4/21 Harris. 2,139,804 12/38 Chandler 26166 2,658,732 11/53 Hall 261-37 2,873,956 2/59 Zubaty. 2,874,944 2/59 Dolza. 2,998,232 8/61 Mennesson 26136 FOREIGN PATENTS 452,246 8/36 Great Britain.

8,659 12/36 Great Britain.

570,513 7/45 Great Britain.

HARRY B. THORNTON, Primary Examiner.

RONALD R. WEAVER, Examiner. 

1. A FUEL INJECTION SYSTEM IN COMBINATION WITH AN INTERNAL COMBUSTION ENGINE HAVING A PLURALITY OF FUEL INTAKE PORTS, WHICH SYSTEM INCLUDES: AN ELONGATE TUBULAR SHELL HAVING A BELL-SHAPED OPEN END PORTION, WITH SAID SHELL BEING CLOSED AT THE OPPOSITE END; A PLURALITY OF TUBULAR RISERS WHICH ARE IN COMMUNICATION WITH THE INTERIOR OF SAID SHELL AND SAID INTAKE PORTS; A RESERVOIR WHEREIN A VOLATILE LIQUID FUEL MAY BE STORED; FIRST MEANS FOR CONTROLLING THE RATE OF FLOW OF AIR THROUGH SAID SHELL TO SAID RISERS AT ANY DESIRES RATE WITHIN PREDETERMINED LIMITS, WITH EACH OF SAID RATES GIVING RISE TO A DIFFERENT PRESSURE IN SAID SHELL; SECOND MEANS FOR DISCHARGING SAID FUEL UNDER PRESSURE FROM SAID RESERVOIR AT A PRESSURE THAT IS PROPORTIONAL TO ENGINE SPEED; THIRD MEANS COMMUNICATING WITH SAID SECOND MEANS FOR FORMING SAID FUEL UNDER PRESSURE INTO A PLURALITY OF TINY DROPLETS BELOW A CRITICAL DROPLET SIZE THAT ARE MIXED WITH SAID AIR TO FORM AN AIR/FUEL MIXTURE IN SAID SHELL PRIOR TO THE ENTRANCE OF SAID MIXTURE INTO SAID INTAKE PORTS, WITH THE RATE AT WHICH SAID DROPLETS ARE FORMED BY SAID THIRD MEANS BEING MATHEMATICALLY RELATED TO THE PRESSURE ON SAID FUEL AS IT ENTERS SAID THIRD MEANS, AND SAID CRITICAL DROPLET SIZE BEING THAT AT WHICH SAID DROPLETS READILY VAPORIZE AT THE TEMPERATURE OF SAID AIR WITH WHICH THEY MIX TO SUBSTANTIALLY COOL THE SAME AND INCREASE THE DENSITY THEREOF; FOURTH MEANS FOR VARYING THE PRESSURE ON SAID FUEL DELIVERED TO SAID THIRD MEANS BY BY-PASSING A PORTION OF SAID FUEL DISCHARGED BY SAID SECOND MEANS BACK INTO SAID RESERVOIR; FIFTH MEANS THAT CONTROLS SAID FOURTH MEANS AND MEANS CONNECTING SAID FIFTH MEANS WITH ATMOSPHERIC PRESSURE AND WITH SAID SHELL, WHICH FIFTH MEANS AS SAID PRESSURE IN SAID SHELL DROPS, ACTUATES SAID FOURTH MEANS TO BY-PASS SAID FUEL AT AN INCREASING RATE TO LOWER SAID PRESSURE ON SAID FUEL AT SAID THRID MEANS TO DECREASE THE RATE AT WHICH SAID DROPLETS ARE FORMED, SAID FIFTH MEANS AS SAID PRESSURE IN SAID SHELL INCREASES, ACTUATING SAID FOURTH MEANS TO BY-PASS SAID FUEL AT A DECREASING RATE TO INCREASE SAID PRESSURE ON SAID FUEL AT SAID THIRD MEANS, WITH SAID INCREASE AND DECREASE OF PRESSURE ON SAID FUEL AT SAID THIRD MEANS SO CONTROLLING THE RATE AT WHICH SAID DROPLETS ARE FORMED THAT AN AIR/FUEL MIXTURE OF UNIFORM COMPOSITION IS FORMED WITH SAID AIR FLOWING THROUGH SAID SHELL, IRRESPECTIVE OF WHICH THIS RATE MAY BE, PRIOR TO ENTRANCE OF SAID AIR INTO SAID FUEL INTAKE PORTS. 